In mathematics, a modular invariant may be

• A modular invariant of a group acting on a vector space of positive characteristic
• The elliptic modular function, giving the modular invariant of an elliptic curve.

• S27 (Munich)
• S.28/43
• S. 287 (113th Congress)
• S2 cells
• S2 (classification)
• S-2D Ag Commander
• S2 expressway (Shanghai)
• S-2F Tracker
• S-2G
• (S)-2-haloacid dehalogenase (configuration-inverting)
• (S)-2-haloacid dehalogenase (configuration-retaining)
• S2 highway (Georgia)
• S2 Hulu Expressway (Shanghai)
• (S)-2-hydroxypropylphosphonate,NADH:oxygen epoxidase
• (S)-2-hydroxypropylphosphonic acid epoxidase
• S2 (Milan suburban railway network)
• S2 (missile)
• S2n
• S2O2
• S2O32-
• S2o design and engineering
• S2o Design and Engineering
• S2P (complexity)
• S2P endopeptidase
• S2 Pro